Jung-Woo Park

Development of real-time-service restoration system for distribution automation system

This paper presents a GA for service restoration in electric power distribution systems. The aim of the service restoration is an emergency control in distribution system to restore out-of service areas as soon as possible when a fault or overload occurs in distribution system. The service restoration problem is formulated as a constrained multi-objective optimization problem. This paper develops GA for the service restoration problem with a constrained multi-objective optimization problem. The effectiveness of the proposed method is demonstrated on service restoration for Koreas Kangdong distribution automation system. The results show the effectiveness of the proposed method for solving the problem.

Application of real-type tabu search in function optimization problems

An optimization solution performance of tabu search is influenced by initial solution, selection of neighbor solution, and size of tabu list etc. In this paper, we proposed a real-type tabu search (RTS) for function optimization, which uses belief space to create a neighbor solution. Belief space is made of upper 60% neighbors to effectively restrict searching limit, so it can improve searching time and local or global searching capability of RTS. Also short-term and long-term memory based tabu lists adequate to RTS are implemented to search a different region. All of theses procedures are independently applied to each determinant value for quick convergance and effective searching process. In order to show the usefulness of the proposed method, the RTS is applied to the minimization problems such as, De Jong functions, Ackley function, and Griewank functions etc., the results are compared with those of genetic algorithm (GA) or evolutionary programming (EP).

study on the development of phthalate plasticizers CRM in PP resin

Phthalate plasticizers are regulated by RoHS, REACH and CPSC as hazardous substances. Responding to these international environmental restrictions, we developed ABS certified reference material (CRM) for determination of phthalate plasticizers such as DMP, DEP, DBP, BBP, DEHP and DnOP. The candidate material has been made with ABS resin widely used in electric and electronic products and 6 kinds of phthalate plasticizers. The making of the material involved a series of processes like extruding, cooling, pelletizing, and drying using twin screw extruder. Then it has been certified according to ISO Guide 35. Using isotope dilution-gas chromatography/mass spectrometry (ID-GC/MS), homogeneity, short-term stability, and long-term stability were evaluated. The certified values were determined by using primary reference material (PRM) of KRISS for traceability. From now on, we will provide ABS CRM to national and international companies and research institutes after certification as certified reference material and registering on COMAR (code of reference material).

Practical Application of Tabu Search to Distribution System Service Restoration in Korea

Abstract This paper develops an efficient Tabu Search (TS) for service restoration in electric power distribution systems. The service restoration problem is formulated as a constrained multi-objective optimization problem. The proposed algorithm begins with an initial solution obtained by dividing and transferring the out-of-service area into several subnetworks according to the margins of adjacent tie feeders. This procedure makes it converge fast to the global optimal state. In addition, we also designed a neighborhood structure and tabu list for distribution system restoration. The final output of the algorithm is presented in the form of a list of ranked alternate supply variants and switching operations. The final choice of the restoration strategy for the out-of-service area is made by the operator on the basis of the list of ranked variants. The effectiveness of the proposed method has been demonstrated by applying it to a practical distribution system in Korea. From the simulation results, the proposed method found the optimal fault restoration strategy. The obtained results were the same as that of the explicit exhaustive search method[8].

Implementation of FLC for speed control of a DC servomotor using real-type tabu search

In this paper, real-type tabu search (RTS) is proposed, which adaptively changes the range of the neighbor solution to be searched each iteration according to an objective function. We design-the adaptive fuzzy logic controller (AFLC) for speed control of DC servomotor using RTS and neural network (NN). In this paper, the operation of the AFLC for speed control of a DC servomotor is composed of two steps. The first step is for optimizing the weighting value of NN and the initial value of input/output gain needed in real-time adjusting input/output gain of a fuzzy logic controller using a NN using the improved RTS. The second step is for real-time changing of the input/output gain of FLC using NN. We apply the proposed AFLC to the speed control of an actual DC servomotor system. Experimental results show that AFLC has the better control performance than a PI controller in terms of settling time, rise time and overshoot.